Opportunistic infections (OI) are a significant cause of morbidity and death in those individuals affected with Acquired Immunodeficiency Syndrome (AIDS). Chemotherapeutic approaches have been only partially successful in reducing the impact of these OI during the course of illness. The major pathogens afflicting those with AIDS include Pnuemocystis carinii, Mycobactertium avium and tuberculosis, Toxoplasma, Cryptosporidium, Microsporidia, CMV and several fungi and yeast. These pathogens invade a wide range of host organs causing penumonia, diarrhea, and encephalitis. This meeting will organize for the first time a forum for those scientists studying OI to share information that will allow for determining important parallels in the pathogenesis and immune response to this apparently diverse group of pathogens. Individual topics to be considered include structural and molecular biology, attachment and invasion of host cells, virulence, innate resistance, host immune response and chemotherapy. The intent of the meeting is to identify any obvious common threads or apparent vast differences among these organisms in the host parasite interaction.